1. Field of the Invention
The present invention relates to a method and apparatus for separating foreign matter from fibers. More particularly, the present invention provides a method and apparatus for separating entrained and/or adherent foreign matter, such as plant parts and other contaminants, from fibers such as cotton or flax.
2. Description of the Prior Art
Cotton possesses its highest fiber quality and best potential for spinning when it is on the stalk. Lint quality of the cotton, after it has been picked and baled, however, depends on many factors, including variety, weather conditions, cultural and harvesting practices, moisture and trash content, and ginning processes. The principal function of a cotton gin is to separate lint (fiber) from seed. But the cotton gin must also be equipped to remove a large percentage of foreign matter from the cotton that would significantly reduce the value of the ginned lint. For purposes of the following discussion, foreign matter is understood to include trash and debris such as leaf particles, motes, grass, and bark, displaced dry or wet lint, wet matter, green bolls, cotton seed, and underdeveloped cotton seed that are associated with the cotton ginning process.
A ginner generally has two objectives: (1) to produce lint of satisfactory quality for the growers"" market; and (2) to gin the cotton with minimum reduction in fiber spinning quality so that the cotton would meet the demands of its ultimate users-the spinner and the consumer. Accordingly, quality preservation during ginning requires the proper selection and efficient operation of each machine that is included in a ginning system.
A thorough description of the cotton ginning process and the various components used is described by Anthony, W. S., et al. (Editors), Cotton Ginner""s Handbook, Agricultural Handbook No. 503, USDA: Agricultural Research Service, December 1994, the contents of which is incorporated by reference herein. In brief, to begin the ginning process, cotton is transported from a trailer, module, or other storage means into a green-boll trap in the gin where green-bolls, rocks and other heavy foreign matter are removed to prevent damage to the machinery. Then, an automatic feed control provides an even, well-dispersed flow of cotton so that the gin""s cleaning and drying system will operate more efficiently. The cotton is subsequently heated in a dryer and cleaned in a cylinder cleaner and stick machine. After drying and cleaning, the cotton is distributed to each gin stand by a conveyer.
The cotton enters the gin stand and the saws in the gin stand grasp the cotton and draw it through widely spaced ribs known as huller ribs. The locks of cotton are drawn through the huller ribs into the lower portion of the seed-roll box. The actual ginning process, i.e., separation of the seed and lint, takes place in the roll box of the gin stand.
From the gin stand, the cotton is conveyed into a lint cleaner for further removing foreign matter such as trash, plant parts, leaf particles, motes, grass, and bark that may remain in cotton after cleaning, extracting, and ginning. The most common lint cleaner in the ginning industry is the controlled-batt saw lint cleaner (SLC). In the SLC, lint from the gin stand is formed into a batt on a condenser screen drum. The batt is then fed through one or more sets of compression rollers and between a feed roller and feed plate to deliver a batt of uniform thickness onto a saw cylinder. The saw carries the fiber under grid bars. While the fibers are on the saw cylinder, they are cleaned of foreign matter by a combination of centrifugal force, scrubbing action between saw cylinder and grid bars, and gravity assisted by an air current. After the cotton has passed through the lint cleaner, the cleaned cotton is compressed into bales which must then be covered to protect them from contamination during transportation or storage.
Although the controlled-batt saw lint cleaner is the most effective cleaning machine in the gin, it is also the most damaging to the fibers. Significant damage to the fibers may occur as they are transferred from the condenser and rollers onto the saw cylinder, and as the fibers are cleaned while on the saw. The saw cylinder rotates at high speed in a direction which is opposite to the flow of cotton from the roller and feed plate. The abrupt change of speed and direction of the flow of the cotton batt as it is engaged by the saw cylinder creates a combing action, which aligns the fibers and gives them a smoother appearance. However, this also subjects the fibers to a high degree of stress, resulting in fiber breakage. Additional fiber damage as well as fiber loss occurs as the fibers are carried by the saw cylinder across the grid bars.
While numerous systems for cleaning cotton fibers have been developed, relatively few systems for the recovery and cleaning of flax fibers have been developed in the United States. Two general types of flax (Linum usitatissimum L.) are grown, flax for fiber and flax for seed. The fiber is extracted from the fiber flax stalks, and is typically used in manufacturing items such as linen apparel. The stalk consists of fiber bundles located between the epidermis or bark surface and an inner wood core (shive), and the processes for the separation of the fibers are difficult and expensive. Moreover, the processes normally used for separation of fiber from fiber flax typically require the stalk to be biologically degraded or retted before mechanical processing. In contrast to fiber flax, the seed flax stalk remaining after the seed has been harvested and recovered is usually considered a waste product. Although the flax in the seed flax stalk can be separated, the conventional processes used for separation of fiber from fiber flax, are not feasible for seed flax stalks.
Thus, despite the improvements in ginning technology, the need persists for an improved ginning system which will effectively clean cotton while reducing fiber damage and loss. Moreover, there is also a need for an improved system for recovering flax fiber from straw.
I have now invented an improved apparatus and method for separating foreign matter from fibers with significantly reduced fiber damage. The apparatus includes:
a) a first housing having an inlet for delivering the fiber containing material therein, and an outlet for discharging partially treated fiber therein;
b) a separation surface positioned within the first housing, which surface includes apertures therethrough which are effective for allowing passage of the foreign matter;
c) a plurality of rotatable first separator cylinders positioned in succession within the first housing above the separation surface, which cylinders include a plurality of projections extending therefrom which are effective for temporarily engaging, moving, and centrifugally releasing therefrom the fibers in the material; the cylinders rotate in the same angular direction such that as the material is engaged by the projections it is transported by successive cylinders through the housing, across the separation surface, and through the outlet;
d) a second housing having an inlet in communication with the outlet of the first housing for receiving partially treated fiber therefrom;
e) a rotatable second separator cylinder disposed in the second housing, which cylinder includes a plurality of projections extending therefrom which are effective for securely engaging and transporting fibers in the material on the cylinder;
f) one or more cleaning bars disposed in the second housing adjacent to the second separator cylinder, such that fibers pass between the cylinder and cleaning bar, while foreign matter in the material is impacted by the bars and removed; and
g) a doffing means for removing said fiber from the projections on the second separator cylinder, which first doffing means may include air blast, vacuum, and a first doffing brush cylinder, wherein the first doffing brush cylinder has an outer peripheral surface operably associated with and rotating in the opposite angular direction as the second separator cylinder, which is effective for mechanically removing the fiber from the projections on the second separator cylinder.
Fiber containing material for treatment is introduced into the first housing in contact with the rotating first separator cylinders. As the fibers are engaged by the projections on the cylinders, the material is both agitated and transported or pulled across the separation surface below the cylinders. The movement of the material across and against this surface effectively scrubs the material, dislodging foreign matter within the material which matter then falls by gravity through the apertures in the surface. In contrast, the fibers engaged by the projections are released therefrom by the centrifugal force generated by the rotating cylinders, thereby conveying the material to successive downstream cylinders in the housing and repeatedly subjecting the material to the cleaning action. Once the fiber containing material is engaged by the last separator cylinder, this partially cleaned material is propelled off of the revolving cylinder toward and through the outlet of the first housing, and directly into the second housing. In a preferred embodiment, propulsion of the partially treated material through the outlet and into the second housing is assisted by providing one or more optional, outwardly extending wipers or paddles on the last separator cylinder.
Fibers in the partially cleaned material delivered into the second housing are seized by and retained on the projections of the second separator cylinder. As the cylinder rotates, the material is transported past the cleaning bars. The fibers retained on the rotating cylinder are subjected to further cleaning to remove any remaining foreign matter by a combination of centrifugal force, the scrubbing action between the cylinder and cleaning bars, and gravity. After the fibers on the cylinder have passed the cleaning bars, the cleaned fibers are removed from the cylinder by the doffing means, whereupon they may be recovered and supplied to a baling machine and/or further treated.
In accordance with this invention, it is an object to provide an improved process and apparatus for removing foreign matter from fibers.
Another object of the invention is to provide an improved cleaner effective for treatment of fiber from cotton or flax.
A further object of the invention is to provide an improved cleaner for effectively cleaning fiber with significantly reduced damage and fiber loss.
Yet another object of the invention is to provide an improved saw-type lint cleaner without any of the condenser, compression rollers, or feed roller and feed plate which are present on conventional lint cleaners.
Still another advantage of the invention is to provide a single cleaner that achieves all the cleaning of flax necessary to produce a usable fiber from chopped straw.
Other objects and advantages of the invention will become readily apparent from the ensuing description.